Characteristics such as the critical current density (J_c) and mechanical property of bronze-processed Nb ₃ Sn superconducting wires have improved with the progress on high-field superconducting magnets such as nuclear magnetic resonance (NMR) magnets. On the other hand, for Nb ₃ Sn wiresused in intermediate magnetic-field applications such as fusion and particle accelerator magnets, the wire parameters have been optimized to realize high J_c around 12 T. In this article, improvements in the J_c and mechanical property of bronze-processed Nb ₃Sn wires based on the activities of Japan Superconductor Technology, Inc. (JASTEC) and Kobe Steel, Ltd. are described.